code: def varargs_agg_func_fixture():
      """
      Register a unary aggregate function
      """
      from pyarrow import compute as pc
  
      def func(ctx, *args):
          sum = 0.0
          for arg in args:
              sum += np.nanmean(arg)
          return pa.scalar(sum)
  
      func_name = "sum_mean"
      func_doc = {
          "summary": "Varargs aggregate",
          "description": "Varargs aggregate",
      }
  
      pc.register_aggregate_function(
          func,
          func_name,
          func_doc,
          {"x": pa.int64(), "y": pa.float64()},
          pa.float64(),
      )
      return func, func_name
  
file_path: arrow/python/pyarrow/conftest.py
imports: import pytest
  import pyarrow
  from pyarrow import Codec
  from pyarrow import fs
  import numpy
label_desc: Use image node_id 6 for calling a global function with example usage: varargs_agg_func_fixture() and returns: func,  func_name, pa